Electrical connector



March 20, 1956 ALDEN 2,739,295

ELECTRICAL CONNECTOR Filed Feb. 10, 1951 United Sttes 2,739,295ELECTRICAL (IQNNECTOR John M. Alden, Needharn, Mass. ApplicationFebruary 10, 1951, Serial No. 210,421 3 Claims. (Cl. 339-258) In theconstruction of female electrical connectors of the molded type it hasbeen found highly desirable to mold the insulation around leads attachedto contacts which form an insert for the mold. This design givesexcellent strain relief as the insulating material becomes homogeneouslybonded to the leads and clips. It also gives better insulation as thereare no openings or uninsulated portions to the connector except theentry for the male pin. However, to get this type of construction it hasbeen the practice to machine or otherwise manufacture the female contactto very close tolerances from eavy gauge stock so that the contactengages the pin with a light push fit without interfering with thesurrounding molded material which acts only as insulation. Themanufacturing of such contacts is slow and expensive and not adapted topunch press or high speed mass produc tion techniques. The resultingconnectors have the additional disadvantages of being large, awkward,heavy, limited in variations in contact pressure and retention forceobtainable, and subject to electrical leakage paths particularly at thepoint where the associated conductor enters the molded portion.

In a broad aspect the invention contemplates an electrical connectorcomprising a recessed contact or insert formed of a resilient materialsuch as a suitable metal which is electrically conducting. The insert isyieldably arranged and constructed, for example as a cup or sockethaving a split side wall, to deform so as to accommodate a conductingcontact member or pin of the electrical component associated with theconnector. The insert is molded in an enclosure of insulating material,such as a suitable plastic whereby the resiliency of the portion ofinsulating material adjacent the cup side wall or other yieldable partof the insert restrains the deformation of such part to increase theelectrical contact pressure upon the mating pin, the value or amount ofthe pressure being determined by the relative dimensions of the insertwall and adjacent insulating material and by the desired retention forceof contact with the mating pin. When an insulating material which isrelatively yieldable is employed, the material is molded into contactwith substantially the entire length of the side wall, the contactpressure being determined by the proportioning of the thicknesses of thewall and adjacent material. If a relatively stitf molded material isused, it is preferable that only a portion of the side wall of theinsert be brought into contact with the surrounding enclosure, clearancebeing provided between the remaining length of the sidewall and themolded material so that the desired contact pressure is obtainable byvarying the length of the contacting portion.

In a more specific aspect one end of an electrical conductor such as aflexible insulated wire is spot welded or otherwise attached to theinsert. The insulation of the Wire is either of the same material asthat of the molded enclosure so that subsequent to the molding operationthe wire insulation and enclosure form a homogeneous structure, or of amaterial having physical characteristics such that an integral bond isformed therebetween during the 2,739,295 Patented Mar. 20, 1956 moldingoperation thereby in either case to eliminate a leakage current path atthe junction point.

These and other objects and aspects will be apparent from the followingdescription of several specific embodiments of the invention which referto a drawing wherein:

Fig. 1 is a side elevation view of a first embodiment of the inventionwhich is adapted to engage the pin of an electrical component such as avacuum tube;

Fig. 2 is a bottom view of the embodiment shown in Fig. 1;

Fig. 3 is a sectional view on line 33 of Fig. 1;

Fig. 4 is a sectional view on line 4-4 of Fig. 2;

Fig. 5 is an isometric view of the insert;

Fig. 6 is a sectional view similar to Fig. 3 of a second embodiment ofthe invention;

Fig. 7 is a sectional view similar to Fig. 4 of the second embodiment;

Fig. 8 is a side elevation view of the male and female portions of aconnector in disengaged relationship;

Fig. 9 is a similar view to Fig. 8 with the connector portions inengaged relationship;

Fig. 10 is an end view of the female portion of the connector;

Fig. 11 is a sectional view of the male and female portions in engagedrelationship; and

Fig. 12 is an enlarged fragmentary sectional view showing the details ofconstruction of the female portion.

The first embodiment of the invention chosen for the purpose ofillustration consists of a connector or cap (Fig. 1) for the mating pinof a vacuum tube which is not shown. The cap 20 comprises a contact orinsert 22 formed (Fig. 3) of a strip of an electrically conductingmaterial such as tinned bronze or brass in the shape of a substantiallycylindrical cup whose internal diameter is in the disengaged positionslightly less than the diameter of the mating pin. The insert cup isprovided with two axial slots or spits 24 diametrically disposed to formtwo side wall portions 25 which yield as the mating pin (not shown) isinserted therein. The closed end of the cup is provided with an aperture26 (Fig. 5) through which one end of a flexible electrical conductorsuch as the insulated wire 28 is inserted. The tip of the back andanchored to the end of the spot welding or soldering.

The assembled insert 22 and wire 28 are then molded in the conventionalmanner well known to those skilled in the art Within a substantiallycylindrical enclosure 30 of a thermoplastic material such aspolyethylene, which is provided with a radially projecting boss 32. Theinsulation surrounding the wire 28 is preferably, although notnecessarily of the same material as that surrounding the insert 22 sothat during the molding operation the boss 32 and the wire insulationare integrally bonded to form a homogeneous piece thus greatlyincreasing the length of the path of the leakage currents. As is bestshown in the isometric view Fig. 5, the end portions 25 of the stripforming the side wall of the insert cup are cut back as at 34 tofacilitate bending of the insert during manufacture, as described below.These cut backs also serve the additional purpose of providing a recesswhich is filled by insulating material of the enclosure 30 during themolding operation thereby to anchor the insert 22 more securely in theenclosure. The flow of the molded material through the aperture 26 inthe closed end of the insert further aids in anchoring the insert in theenclosure.

It is to be particularly noted that an insert 22, such as describedabove, can be readily manufactured from a strip of light gauge sheetmaterial by a multiple action die in a simple punch press operation withresulting economies in manufacturing costs. Because of the reinforcingof the pin contacting insert side wall material of the enclosure 30, thegauge of the material of wire 28 is then bent cup, for example bycontact pressure against the mating pin (not shown) is' obtained.

In the above described embodiment, the reinforcing portion of theinsulatingmaterialiextends the enti'relength of the insertside wallportions 25.- When, however the enclosure is molded of a more rigidplastic material, rather than reducing the thickness of the insulatingmaterial' to the point: of possible electrical breakdown, it isadvantageous to provide only partial backing for the insert side wallportions as in the modified cap 26a shown in Figs. 6 and 7; The cap 202:has the same advantages and features and is generally similar to the capdescribed in detail heretofore with the exception that the enclosure ais made of 'a less yieldable material and a clearance provided betweenthe lower side wall portions 25' of the insert 22 and the surroundinginsulating material as at- (Figs. 6 and 7) thereby reducing. thereinforcing action of the insulating material so that the desiredcontact pressure can be obtained without dangerously reducing thethickness of the insulation. a

The above described principle is not limited to tube cap connectors norto inserts having a cylindrical socket, but as is shown in Figs. 8through 127 can be applied to the female portion of a high voltageconnector which mates with the pin of a male portion as is shown in Fig.11. In this connector the socket insert 52' is generally triangular inshape as is shown in Fig. 10 having, a split along the apex to permitthe two adjacent sides to separate as the pin of the male portion 55 isinserted. The side of the insert 52 opposite the apex slit is extendedon both ends and bent back in opposite directions. The forward end isbent back upon itself to form a tab 54 to which the connecting wire 28bis welded or otherwise anchored. The rear end 56 is bent at rightanglesto close thev bottom of the insert.

The insert 52 is preferably manufactured by a punch press operation andmolded in the surrounding insulating enclosure so that the light gaugemetal of the side walls of the insert 52 are reinforced by thesurrounding insula tion, the thickness of which is determined by thecontact pressure desired in an analogous manner to that describedheretofore in connection with the tube cap 20. Although in the connectorshown, the walls of the insert 52 are reinforced along their entirelength, it is also possible to provide clearance between a portion ofthe insert sidewall and the adjacent insulating material in a mannersimilar to that described in connection with the tube cap 20a shown inFigs. 6 and 7 so as not too greatly to reduce the thickness of theinsulating material.

A further feature of the female connector 50 is two opposed offsets 60(Fig. 10) indented in the sidewalls of the insert 52. These offsets60are backed by the resilient insulating material so that they act as aclick cletent exerting considerable retention force upon engaging acorresponding groove in the male connector portion 55.

It should be understood that the present disclosure is for the purposeof illustration only and that this invention includes all modifications.and equivalents which fall within the scope of the appended claims;

I claim:

1. In an electrical connector; a; unitarycontact having an integralportion for yielding receiving a mating contact member, a lead wireconnected to said contact, an insulating covering on said wire, and anenclosure of resilient, insulating material molded to a part of saidyielding portion to resist yielding of said part when said memher isreceived and spacedfrom another part of said yielding portion so as topermit yielding of said other part unimpeded by pressure from saidenclosure when said enclosure is formed of relatively stifi yieldingmaterial, said enclosure being intimately bonded to said insulationmechanically to secure the insulated wire to the enclosure.

2. In an electrical connector, a contact having a portion for yieldinglyreceiving a mating contact member, a lead wire connected to saidcontact, an insulating covering on said wire, and an enclosure ofinsulating material molded to said contact, said enclosure beingintimately bonded to said insulation mechanically to secure theinsulated wire to the enclosure,v said contact and enclosure havingyieldingly parallel walls, said contact walls being flexible and having freeends, and said enclosure wall having affi'rst portion spaced from saidfree end contacting and pressing on the yielding contact wall and asecond portion; with lateral clearance from said free end, therebyreducingthe reinforcing action ofthe insulating material so that thedesired contact pressure can be obtained independentlyof therelativestifiness of the enclosure.

3. In an electrical connector, a contact for yieldingly receiving amating contact member, a lead wire connected to said contact, aninsulating covering on said wire, and an enclosure for insulatingmaterial molded to said contact, said enclosure being intimately bondedto said insulation mechanically to secure the insulated wire to. the

enclosure, said contact comprising a transverse wall. and a split sidewall extending therefrom, a portion of said side wall adjacent saidtransverse wall being of reduced width flexibly to hinge the free end ofthe side wall to saidl'transverse wall, said enclosure having a parallelwall with. an inner portion contacting and pressing on said' reducedportion and an outer portion with lateral clearance from. said free end,thereby reducing the reinforcing action ofthe insulating material sothat the desired contact pressure,

can be obtained independently of the relative stifiness of theenclosure.

References Cited in the file of'this patent UNITED STATES PATENTSKjell-Berger Aug; 8, 19501

